1. See concern. 3. To take care,pains,trouble (to do something) implies watchful, conscientious effort to do something exactly right. To take care implies the performance of one particular detail: She took care to close the cover before striking the match. To take pains suggests a sustained carefulness, an effort to see that nothing is overlooked but that every small detail receives attention: to take pains with fine embroidery. To take trouble implies an effort that requires a considerable amount of activity and exertion: to take the trouble to make suitable arrangements.

Usage note

13.Couldn't care less, a phrase used to express indifference, is sometimes heard as could care less, which ought to mean the opposite but is intended to be synonymous with the former phrase. Both versions are common mainly in informal speech.

Different sense evolution in related Dutch karig "scanty, frugal," German karg "stingy, scanty." The sense development in English is from "cry" to "lamentation" to "grief." Meaning "charge, oversight, protection" is attested c.1400, the sense in care of in addressing. To take care of "take in hand, do" is from 1580s.

v.

Old English carian, cearian "be anxious, grieve; to feel concern or interest," from Proto-Germanic *karojanan (cf. Old High German charon "to lament," Old Saxon karon "to care, to sorrow"), from the same source as care (n.). OED emphasizes that it is in "no way related to L. cura." Related: Cared; caring.

To not care as a negative dismissal is attested from mid-13c. Phrase couldn't care less is from 1946; could care less in the same sense (with an understood negative) is from 1966. Care also figures in many "similies of indifference" in the form don't care a _____, with the blank filled by fig, pin, button, cent, straw, rush, point, farthing, snap, etc., etc.

Positive senses, e.g. "have an inclination" (1550s); "have fondness for" (1520s) seem to have developed later as mirrors to the earlier negative ones.